Magnetic track brake system



July 6, 1937. r. H. scHoEPF ET AL MAGNETIC TRACK BRAKE SYSTEM Original Filed Feb. 3, 1936 INVENTOR THEODORE H. ScHoE r 0A we M. HITCH/5 VIII;Z1 IIIII AT TQRNEYS February-3, 1936, is provided for opening and closing'the energizing circuit independently of the operation of the normally closed switch which includes the switch blades 2| and 22. In the operation of the brake mechanism of our invention, the application of the brake shoe to the 'rail 1 is dependent upon energization of the coil 9. If, after application, the coil energizing circuit is interrupted, the brake coil 9 will be deenergized and the brake shoe I will be removed from contact with the rail 1. For this purpose means operated through the heat-responsive element I8, is provided for causing the interruption of theenergizing circuit for the coil 9 by removal of the switch blade 2| from engagement with the switch contacts l3 and I4 and by removal of the switch blade 22 from engagement with the switch contacts I! and |'8 when the temperature of the brake shoe exceeds a predetermined value.

This means comprises a relay generally designated 23 which includes a solenoid coil 24 having one terminal thereof connected by means of wire 25 with one terminal of the heat-responsive element l8 and having the'other terminal thereof connected by means of the wire 26 with the heatresponsive element It). The relay 23 includes also a solenoid armature 21 provided at its end with the switch blade 28. The relay 23 includes also a pair of switch contacts 29 and 30 which are adapted to be engaged by the switch blade 28 when the solenoid coil 24 is energized. Nor-- mally,.the-solenoid coil 24 is de-energized and the switch blade 28 is removed from engagement with the switch contacts 29 and .38 respectively. As shown in Figure 1 the parts are in the position taken when the solenoid coil 24 is energized by the fiow of current in the solenoid energizing circuit due to the current-producing action of the heat-responsive element l0 under the influence of temperature'above a predetermined value existing in the brake shoe.

Means is provided whereby energization of the solenoid coil 24, as described above, causes the removal of the switch blades 2| and 22 from their respective contacts of the brake coil energizing circuit whereby to interrupt the brake coil energizing circuit and cause the brake shoe I to be deenergized. This means comprises solenoid actu- 1 ated means for engaging and removing from engagement' with their. respective contacts; the

switch blades 2| and 22. As illustrated in Figure- 1, the switch blades 2| and 22 are secured in spaced relattion on the solenoid armature 3 I. The

solenoid'af ature 3| cooperates with the solenoid coil 32 'to properly position the switch blades 2| and 22. t

The solenoid armature 3| is normally biased to the right, as seen in'Figure 1, by the spring 3|a.

When, however, the solenoid 32 is energized, the I biasing force of the spring 3|a is overcome, and

the solenoid armature .3| takes the position shown in Figure 1 The switch contact 29 of the relay 23 is connected by the wire 33 with one terminal of the solenoid coil 32. The opposite terminal of the solenoid coil 32 is connected by the wire 34 with one terminal of the'power source 35. *The opposite terminal of the power source v35 is connected by means of'wire 36 to the switch contact 38 of the relay 23. Thus, when the switch blade 28 engages the switch contacts 29 and 30, a circuit is completed from the switch contact 30 through wire 36 to power source 35, through wire 34 tosolenoid coil 32 and from solenoid coil 32 through wire 33 to switch contact 29 and through switch blade 28 to switch contact 30. This energizes the solenoid coil 32 and causes the parts to take the position illustrated in Figure -1 whereinthe switch blades 2| and 22 are so positioned as 'to interrupt the energizing circuit for the coils 9 of .the brake shoe.

Operation coil 32 is therefore de-energized and the switch blade 2| is in engagement with the switch contacts |3and I4 and the switch blade 22 is in engagement with the switch contacts l1 and I8.

When the temperature in the brake shoe exceeds a predetermined amount, suflicient current is generated in the heat-responsive element Hi to energize the solenoid coil 24 and thus to cause the solenoid armature 21 to be thrust upwardly to the position shown in Figure 1 whereby to complete the energizing circuit for the solenoid coil 32. The s01enoid c0i1 32 is thus energized whereby to cause leftward movement of the solenoid armature 3| to the position shown in Figure 1' whereby to remove the switch blade 2| from'engagement with switch contacts l3 and I4 and to remove the switch blade 22 from en gagement with the switch'contacts I1 and I8. It is, of course, understood that other heatresponsive switch mea s may (as shown in Figures 4 and 5) be substituted for the thermocouple ||l illustrated and described above. It is further to be understoodthat, where the current generated by the above described thermocouple Ill or equivalent means is suflicient to energize the solenoid coil 32, the relay 23 may be omitted. The solenoid and switch operating mechanisms shown are illustrative only, and it is further to be understood that other ,equivalent mechanical or other means may be used'in the same relation to perform the same function. It is further to be understood that solenoids of widely varying'operating characteristics may be used and such means as springs, dashpots, counterweights and the like may be used to control the operating characteristicsthereof as may be desired. The power source 35 may comprise any suitable source of power such as a-battery or other power source.

- D movable switch contact 39 at'the other end. The

switch member "comprises laminations 4| and 42 of different metals having varying co-eilicients of linear expansion. The co efilcient of expansion of the lamination 4| is less than the co-efilcient of expansion of the lamination 42.v The heat responsive switch mechanism is shown in its normal position in Figures 4 and 5 and, in that position, the contacts 38 and 39 are separated, whereby the heat responsive switch is open. When, however. the switch mechanism is sufliciently heated, the greater linear expansion of thelamination 42 over that of the-lamination 4| will cause the switch member 40 to straighten out and place contacts 33 and 39 in engagement. When this occurs, the circuit is closed through the heat responsive switch mechanism.

' As shown in Figure 4, the wire 26 connects the solenoid 24 to the wire 36 which leads to one terminal of the source of power 35. 'The opposite terminal of the solenoid 24 is connected by the wire 25 to the wire 34 which leads to the opposite terminal of the source of power 35. The abovedescribed switch mechanism is inserted in the wire 25 and, as may be clearly understood, the circuit provided by wires 25 and 26 is normally open and the solenoid 24 dc-energized. The solenoid armature 3| is then biased to the right by the spring 3m and the brake energizing circuit is complete. When, however, the heat in the brake shoe is sufllcient to cause operation of the heat responsive switchmechanism to close the circuit by engagement of contacts 38 and 39, thesolenoid 2.4 is energizedto place the switch plate 28 in engagement with contactsjs' and 30- and thus complete the energizing circuit for the solenoid 32. The solenoid armature 3| then takes the positionillustrated inFlgure l.

In Figure 5, .the above-described heat respon; sive switch element is shown connected directly .in the energizing circuit of the solenoid 32, the re lay 23 being omitted. When the heat responsive 'switch mechanism is so utilized, the wires 33 and 35 are connected respectively to the stationary contact "and the heat responsive member 40.

' the scope o! Thus, when the brake shoe is sumciently heated to cause the contacts 33 and 39 to be engaged,

the energizing circuit for the solenoid 32 is energized, whereby to overcome the force of the biasing springam .and place the solenoid armature 3| in the position shown in Figure 1. The abovedescribed heat responsive switch mechanism is preferably of similar proportions to the heat responsive element l0 and is preferably so mounted. with respect to the brake shoe. However, when we claim as new and desire to secure by Letters.

Patent is: a

, "1'. In a magnetic track brake system including a bralre shoe having a core, a coil, and an energizingcircuit therefor; switch means'in said circuit, solenoid means for operating said switch switch means when a predetermined temperature means to open-and close said circuit, and 'means' responsive to the temperature of said shoe adapted to cause said solenoid meansto open said oirthe shoe is reached. 7

2. Ina magnetic track brake system including a brake shoehavi-ng a core, a coil, and an e'ner .gizing circuit therefor; switch-means in said cir-' cult, solenoid means for operating said. switch' .meansto open andclose said circuit, and means including a thermocouple in said shoe adapted to ='-cause said solenoid means to open the switch means when a predetermined temperature of the shoe is reached whereby to prevent overheating oi the"shoe.

3. In a magnetic track brake-system including.

.a brake shoe having a core, a coil, and an energizing circuit therefor; switch means in said cir-., cult, solenoid means ior operating said switch means to open and close said circuit, relay means for operating said solenoid. means and a thermocouple in .said shoe. adapted, when a predetermined temperature of the shop is reached, to cause said relay means to operate said solenoid means to open said switch means, whereby'to prevent excessive temperature of the shoe.

4. In a'magnetic track brake system including a brake'shoe having a core, a coil, and opener-- 'gizing circuit thereto switch means in said cir cuit,-. solenoid means for operating said switch means to open and close said circuit, relay means for operating said solenoid means, and means responsive to the temperature oi said brake shoe adapted, when a predetermined temperature is reached, to cause said relay means to operate said solenoid means to open said-switch means and arrest the energization of the shoe'whereby to prevent the production 01 excessive temperature in said shoe.

5. In a magnetic track brake system including a brake shoe having a core, a coil, and an energizing circuit therefor; switch means in said" brake coil energizing circuit. an energizing circuit ior said switch means, and temperature responsive switch 'means'in said shdeconnected in said switch energizing circuitand responsive to the temperature in said brakeshoe,

said temperature responsive switch means being adapted, when said temperature exceeds a predetermined value,'-to cause said switch means to 'open said energizing circuit.

6. In a magnetic track brake system including a brake shoe having a core, a coil, and an energizing circuit thereior; normally closedswitchmeans in said circuit, solenoid meansior openlug said switch and means .responsive to the temperature insaid brake shoe for energizing said solenoid means cTpened thereby.

7. In a magnetic track brake a brake shoe having a core, a coil, and an enersizing circuit therefor; normally closed switch tocause said switch means to be means in said circuit solenoid means adapted, when energized, to open said switch means, and

means responsive to the temperature in the core including oi. said brake shoe for energizing said solenoid means when the temperature oi ceeds a predetermined value. I

8. In *amagnetic track brake system includ- .ing a brake shoe having a core, a coil, and an energizing circuit therefor; normally open temperature responsive circuit switch means in said brake shoe adapted to close when the tempera.-

said core ex-'.

ture in said shoe-exceeds a predetermined amount, a circuit operatively connected to'said temperature responsive circuit switch means and having tlierein aisolenoid coil; and means includ- Inga relay responsive to the energizeticn of said solenoid coil i'oi' causing'interruption oi the brakecoil Cm circuit when said solenoidjcoil is energised by closingoi' said temperature responsive circuit switch means.

scnoner'. DAVID M, i 

